Novel bis-aryloxazolyl ethylene optical brightening derivatives



United States Patent 3,178,421 NOVEL BIS-ARYLOXAZOLYL ETHYLENE GPTI- CAL BRIGHTENING DERIVATIVES Kenzo Kouishi, Nishinorniya, Masao Wakae, Osaka, and

Mitsuhiro Gui, Hirakata, Japan, assignors to The Goveruor of Osaka Prefecture, Japan, ()saka, Japan No Drawing. Filed Dec. 28, 1960, Ser. No. 78,825

Claims priority, application Japan, Jan. 9, 1960, 35/717 2 Claims. (Cl. 260-240) The present invention pertains to a process for the optical brightening of textile materials. More particularly, this invention relates to a series of water-soluble onium compounds which can be profitably employed in the form of aqueous solution'for the optical brightening of textile materials, such'as synthetic fibers made from polyacrylonitrile or its copolymers, polyamide, polypropylene, polyethylene or polyvinyl-acetal; artificial fibers made from viscose rayon or cellulose acetate; and natural fibers like cotton.

The brightening agents of'this invention comprise ,5- bis [methylene aryloxazol-yl (2)] ethylene w,w'- onium halides andtheir zinc chloride double salts, having the structural formula wherein A and A represent respectively a benzene nucleus or a naphthalene nucleus; R and R stand for respectively a hydrogen atom, a methyl group or an ethyl group; B is an onium salt-forming compound residue, and X a halogen atom.

The brightening agents of this invention are all watersoluble. Materials to be brightened are accordingly simply dipped in an aqueous solution of pH 2 to at a temperature ranging from room temperature to 130 C. at the highest. The material is then rinsed and dried as usual in the art.

The pH value and the temperature of the aqueous solution being employed are accommodated according to the property of the material being brightened. Synthetic fibers made from polyacrylonitrile or its copolymers, for instance, are profitably treated in an aqueous solution of pH 2 to 7. To brighten polyamide fibers like nylon or other fibers made from polyvinylacetal or cellulose acetate, an aqueous solution of pH 6 to 8 is employed with advantage.

The temperature employed in this invention ranges from the room temperature to 130 C. at the highest, as stated before. A pressure vessel is also employed at a temperature over 100 C. The commercial temperature, however, is confined to the range of 70 to 110 C., both because the lower temperatures prolong the dipping process and because some of the materials to be brightened cannot endure the higher temperatures. Materials soaked with the brightening solution can be steamed in a closed vessel.

Satisfactory results are obtained in a 0.001 weight percent solution of the product of this invention. No marked improvements can be obtained with elevated concentration. The solution is adjusted to a desired pH value by the addition of an organic acid or an inorganic or organic acid salt. The dipping period of time ranges from 20 to 60 minutes or thereabouts.

The brightening agents of this invention can be dissolved in most of dyeing and bleaching baths, so that the material can be optically brightened simultaneously with the dyeing and bleaching process with much profit.

The brightening substances. of this invention can also be employed together with finishing agents such as starch 3,178,421 Patented Apr. 13, 1965 and synthetic resin and washing agents like soap and alkylaryl sulfonate. The brightening operation can accordingly be performed concurrently with finishing operation including crease-proof processing or with washing operation.

The zinc chloride double salts of this invention can be purified in an easy and simple manner, because of their inclination to salt out. Said double salts, however, have no substantial differences in the way of employment and brightening effect from the onium salts of this invention.

The brightening agents of this invention possess a marked substantivity for all kinds of hydrophilic fibers and penetrate into the fibers themselves to be steadfastly fixed therewith, which is presumably due to the'cationic property of the agents. The material comes to yield an excelled fastness to sun light, ultraviolet light and washing as well, exhibiting arr-intense violet-blue fluoresc'encein ultraviolet light.

In the prior art, conventional brightening agents are all required to be dissolved in aqueous media with dispersants, because they are water-insoluble. Carriers and auxiliary agents are occasionally added, and a pressure apparatus of specific device is employed. Those agents "which are water-soluble failed to produce expected results in improving thewhiteness of the material.

Unlike those agents employed in the conventional art, the brightening substances of this invention are all applicableto any kind of fibers as specified before, because of the high water-solubility and aflinity for the fibers. Even those materials which are made from, for instance, polyacrylonitrile or its copolymers, and which are hard to brighten in the prior art, canbe easily treated with the products of this invention. And the form of fibers treated in this invention comprises filament, staple-fiber, yarn, textile and film.

To prepare the onium halides of this invention, one mol of u,fl-bis-[aryloxazolyl-(2)]-ethylene is reacted at 20 to C. and in the presence of sulfuric acid and chlorosulfonic acid with 2 mols of hydrogen halide and 2 mols of formaldehyde in the form of paraformaldehyde or with 2 mols of dihalogenomethyl ether to introduce the halogenomethyl group to each of the aryl rings of the ethylene compound. An onium salt-forming compound, such as pyridine, picoline, lutidine and trialkylamine, is then added. Thiourea and its derivatives and trihydroxyalkylamine are not employed in this invention as onium saltfor-ming agents, since the resulting product is colored.

Another method for preparing the onium halides of this invention is to react at \20 to 80 C. and in the presence of sulfuric acid and chlorosulfonic acid one mol of a,B-bis-[aryloxazolyl-(2)]-ethane with 2 mols of hydrogen halide and2 mols of formaldehyde in the form of paraformaldehyde or with 2 mols of dihal-ogenomethyl ether to introduce the halogenomethyl group to each of the aryl rings of the starting material. An onium saltforming agent as specified before is added. The resulting product is then oxidized in water or in an organic medium, preferably in glacial acetic acid, at 50 to C. with a mild oxidant like mercuric acetate, mercuric oxide, hydrogen peroxide or nitrobenzene toproduce the desired halide of this invention.

The halogenomethylating reaction as specified above is performed mucheasier with sodium chloride or sodium bromide than with hydrogen chloride, since the reaction takes place with the hydrogen halide formed in the mixture by said salt with sulfuric acid.

The double salts of this invention are derived from the final products as specified above by dissolving in an aqueous solution thereof equi-molar zinc chloride. The purity of the product is improved merely by repeate filtration and recrystallization.

save r21 Of all the compounds of this invention having the structural formula as stated before, a,5-bis-[5-methylmethylene benzoxazolyl-(2) -ethylene-w,w'-dipyridinium 'chloride possesses a marked optical brightening effect due to the high water-solubility and affinity for the fiber.

Preferred embodiments of the present invention are illustrated in the following examples, the parts and percentages being by weight unless otherwise stated:

PREPARATION OF a,/3-BIS-[5-METHYL-METHYL- ENE-BENZOXAZOLYL (2)] ETHYLENE-w,w' DIPYRIDINIUM CHLORIDE Example 1 To a mixture of 20 cc. of 98 percent sulfuric acid and 6 grams of paraformaldehyde are added dropwise at to C. 75 cc. of chlorosulfonic acid. 5 grams of a,;3-bis- [5-methyl-benzoxazolyl-(2)]-ethylene are then added with stirring. After ensuing agitation for 30 minutes, 5 grams of sodium chloride are added portionwise at to C. The reaction mixture is kept at 60 C. for 48 hours, then allowed to stand overnight at room temperature, and

I poured in ice water. Precipitation products are collected,

washed with water until the filtrate becomes neutral, and dried, yielding 5 grams of crude chloromethylated sub stance, which is further purified to 3 grams of pure substance by repeated recrystallization with benzene.

The entire amount (3 grams) of chloromethylated product thus purified is then boiled for 8 hours with 3 grams of pyridine, 10 cc. of acetone and 10cc. of methyl alcohol. Solvents being driven out, the resulting residue is dissolved in methyl alcohol to remove the insoluble substance. The filtrate is concentrated, treated with acetone, and allowed to precipitate at room temperature. The resulting precipitate is filtered, washed with ispropyl ether, and dried in vacuo, yielding 2.5 grams of the desired onium compound of this invention, which dissolves easily in water and gives off an intense blue fluorescent light in ultraviolet light. 11 grams of dichloromethyl ether employed instead of 6 grams of paraformaldehyde react in the same manner as described above.

Example 2 To a mixture of 467 grams of 98 percent sulfuric acid and 36 grams of paraformaldehyde are added dropwise at 0 to 5 C. 292 grams of chlorosulfonic acid. The paraformaldehyde being completely dissolved with stirring, 29.2 grams of n p-bis-[S-methyl-benzoxazolyl-(2)]- ethane and then 58.4 grams of sodium chloride are added portionwise. The mixture is then stirred at to C. for 48 hours, and poured in ice Water. The precipitate is filtered, washed and dried, yielding a white crystalline substance having the formula 5 grams of the product thus obtained are then dissolved in 350 grams of chlorobenzene at 125 to 130 C. 3.5 grams of active carbon are added. The solution is filtered while hot. To the filtrate are then added 98 grams of pyridine. The miXIUI? i Stirred for 24 hours at C.

The resulting slurry residue is filtered, rinsed with chlorobenzene, and then benzene, and dried, yielding pyridinium salt almost quantitatively. The product is purified by dissolving in methanol, decolorizing with active carbon, and recrystallizing with acetone.

34 grams of pyridinium salt thus prepared are then dissolved in 170 grams of glacial acetic acid. 39 grams of mercuric acetate are added at 25 to 30 C. The mixture is stirred at C. for 3 hours. The mercury is separated by filtration while the mixture it hot. The acetic acid is driven out by distillation in vacuo. To the resulting residue are added 70 grams of methanol. The extract is then decolorized with active carbon, and removed of methanol, yielding the desired onium halide of this invention in the form of brown yellow crystals.

26.5 grams of mercuric oxide employed instead of 39 grams of mercuric acetate result in the same reaction as stated above.

PREPARATION OF DOUBLE SALTS Example 3 7 grams of the onium compound prepared according to Example 1 are dissolved in 210 cc. of water. 37 grams of 48 percent zinc chloride and 24.2 grams of sodium 'chloride, both dissolved in 170 cc. of water, are then added at 10 C. The mixture is allowed to precipitate at room temperature, and the precipitation product is filtered and dried, producing a pale yellow double salt of one mol of onium halide and one mol of zinc chloride. Yield is 97 percent for theoretical.

BRIGHTENING TEST Example 4 Polyacrylonitrile fabrics are treated for 30 minutes at C. at a bath ratio of 1:50 in an aqueous solution containing per liter 0.01 gram of the compound having the formula Example 5 Mixed fabrics of 55 parts of polyacrylonitrile and 45 parts of cotton are treated for 60 minutes at 80 C. in a bath ratio of 1:50 in an aqueous solution adjusted to pH 6 and containing per liter 0.01 gram of the double salt obtained according to Example 3. The material is rinsed and dried. Uniform whiteness is obtained.

The resulting fabric is then treated for 60 minutes at 75 C. at a bath ratio of 1:50 in an aqueous solution containing per liter 2 grams of sodium chlorite and adjusted to pH 3 with 2 grams of 80 percent formic acid. After being rinsed, the material is further treated for 20 minutes at 50 C. in a bath ratio of 1:40 in an aqueous solution containing per liter one gram of sodium bisulfite. The material is then rinsed and dried, yielding a pronounced whiteness.

Example 6 Polyacrylonitrile fabrics are padded in an aqueous solution containing per liter grams of the double salt preparation obtained according to Example 3. The material is then squeezed until the entire weight is reduced to twice the original, steamed at 105 C. for 10 minutes in a closed vessel, and treated with sodium chlorite for minutes at 95 C. in a manner as illustrated in Example 5. After being rinsed, the material is further treated at 50 C. for 20 minutes in a bath ratio of 1:40 with 0.1 percent sodium bisulfitc. The material is then rinsed and dried, producing an enhanced whiteness almost similar to that whiteness obtained according to Example 4.

Example 7 Polyvinylacetal fabrics are treated in a bath ratio of 1:50 for 60 minutes at 75 C. in a bath containing per liter 0.01 gram of one-bis-[S-methyl-methylene-benzoxazolyl-(2)]-ethylene-w,w'-dipicolinium chloride and adjusted to pH 8 with a small quantity of sodium carbonate. The material is then treated with sodium chlorite and sodium bisulfite in a manner as illustrated in Example 5. The whiteness obtained is markedly improved.

Cellulose acetate and nylon fabrics treated in the same manner as described above also produce the same satisfactory result.

Example 8 250 parts of nonionic washing agent consisting of a condensation product of 40 mols of polyoxymethylene and one mol of oleyl alcohol, are dissolved in water with 3.5 parts of the onium compound prepared according to Example 1 and 31.5 parts of sodium sulfate'to make a 0.1 percent onium compound solution.

Polyacrylonitrile fabrics are washed for 80 minutes at 20 C. with said aqueous solution in a bath ratio of 1:50. The resulting material yields a more pronounced whiteness than the material merely treated with the washing agent containing no onium compound.

What is to be further noticed in connection with the brightening tests is that the materials optically brightened in the manners as illustrated in Examples 4 through 8 can be further treated with customary soaps, synthetic detergents and finishing agents without affecting in any way the whiteness obtained and the fastness thereof.

What We claim is:

1. A compound selected from the group consisting of an u,fi bis[methylene aryloxazolyl-(2)]-ethylene-onium halide of the formula R! o 0 R B-HQO N/ N GH -B wherein each of A and A is a member selected from the group consisting of a benzene nucleus and a naphthalene nucleus;

each of R and R is a member selected from the group consisting of hydrogen, methyl and ethyl;

B is a radical selected from the group consisting of pyridine, picoline, lutidine and trialkyl amine, and

X is halogen;

and zinc chloride double salt thereof.

2. A compound of the formula References Cited in the file of this patent UNITED STATES PATENTS 2,463,264 Graenacher et al. Mar. 1, 1949 2,482,392 Meyer et a1 Oct. 4, 1949 2,488,289 Meyer et al Nov. 15, 1949 2,620,282 Fry et al Dec. 2, 1952 2,646,355 Zweifel et al July 21, 1953 2,809,123 Keller et al. Oct. 8, 1957 2,842,545 Duennenberger et a1 July 8, 1958 2,873,206 Geigy et al. Feb. 10, 1959 2,910,472 Siegrist et al. Oct. 27, 1959 3,019,221 Shoer et a1 Jan. 30, 1962 FOREIGN PATENTS 835,892 Great Britain May 25, 1960 OTHER REFERENCES Luabs: Chemistry of Syn. Dyes and Pigments (pages 608-1955). 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN A,B-BIS(METHYLENE-ARYLOXAZOLYL-(2)-ETHYLENE-ONIUM HALIDE OF THE FORMULA 